Field of the Invention
The invention relates to an electronic device having at least one semiconductor chip and a method for producing the electronic device.
Electronic devices having one or more semiconductor chips are not usually combined with passive components in a housing, particularly if the electrical values of the passive component are intended to be variable after the mounting of the electronic device on a printed circuit board. This is the case for example with resistances, inductances or capacitances for radio-frequency applications which are intended to be trimmable to their final electrical value after their interconnection in order to compensate for tolerances of the electrical properties of the semiconductor circuits assigned to them. The trimmability after incorporation is usually ensured by the adjustable passive components being mounted spatially separate from the semiconductor circuits assigned to them and having a mechanical access for intervention and for varying the electrical values.
A configuration containing an IC module with passive components is disclosed in German Patent DE 197 28 692 C2, corresponding to U.S. Pat. No. 6,215,171.
It is accordingly an object of the invention to provide an electronic device having a trimming possibility and at least one semiconductor chip and a method for producing the electronic device which overcome the above-mentioned disadvantages of the prior art devices and methods of this general type, which combines a trimmable passive component with a semiconductor component in a manner that saves as much space as possible.
With the foregoing and other objects in view there is provided, in accordance with the invention, an electronic device. The electronic device contains at least one semiconductor chip, at least one trimmable passive component electrically conductively connected to the semiconductor chip and has electrical values that can be varied, a rewiring structure electrically conductively connected to the semiconductor chip, and a housing made of plastic enclosing the rewiring structure, the semiconductor chip and the trimmable passive component.
According to the invention, the electronic device has the semiconductor chip and the passive component, which is electrically conductively connected to the latter and whose electrical values can be varied. At least the semiconductor chip is electrically conductively connected to the rewiring structure which, together with the at least one semiconductor chip and with the at least one passive component, is enclosed by a housing made of plastic.
The particular advantage of such an electronic device resides in the compactness that can be achieved for the device and the very small structural height thereof. In addition, the trimmability of the passive component after assembly can be made possible in this way. This can be effected for example mechanically or else by a laser.
One embodiment of the invention provides for the electrically conductive rewiring structure to have a three-dimensional structure, which is associated with considerable advantages with regard to the compactness that can be achieved for the device. The electrically conductive layer of the rewiring structure is formed essentially from aluminum, nickel, gold, silver, palladium and/or copper. All of these metals are particularly well suited to the production of electrically conductive connections with minimal electrical resistance.
A further embodiment of the invention provides for the passive component to be electrically conductively connected to the semiconductor chip by two bonding wires. What is designated by semiconductor chip in the present context may also be a simple semiconductor component, such as, for example, a transistor, a field-effect transistor, a diode or the like. However, the semiconductor chip may also be a more highly integrated module having a multiplicity of contact areas. In this case, the rewiring structure must likewise have a multiplicity of contact pads which are electrically conductively connected to the contact areas of the semiconductor chip via bonding wire connections or, for example, by flip-chip technology.
Equally, in a further embodiment of the invention, the passive component may be electrically conductively connected to the semiconductor chip by flip-chip technology, which has, in particular, the advantage of an extremely compact and reliable connection that can be produced in a simple manner.
The passive component may be, for example, an adjustable electrical resistor, a capacitor having a variable capacitance or a coil having a variable inductance. All of the combinations mentioned make it possible to realize an extremely compact device containing the semiconductor chip and the passive component that can be regulated to its final value after mounting.
Preferably, in accordance with a further embodiment of the invention, the semiconductor chip and the passive component are insulated from one another by an insulator. The insulator preferably has through contacts that produce an electrically conductive connection between electrical terminals of the passive component and the second bonding wires or contact bumps of the semiconductor chip.
A method according to the invention for producing an electronic device in accordance with one of the embodiments described above has the now described method steps. A thin, metallic carrier substrate is provided, whose area preferably corresponds to a plan of an electronic device to be produced. A photofilm layer is applied to the substrate and exposed. Afterward, the photofilm layer is developed, the developed regions are filled with an electrically conductive layer and the photofilm layer is removed, as a result of which a three-dimensional rewiring structure is formed from the electrically conductive layer. Afterward, the passive component, the insulator and the semiconductor chip are applied on the first surface of the carrier substrate, after which electrical connections are produced between the semiconductor chip, the passive component and the rewiring structure. A housing made of plastic is provided around the semiconductor chip, the insulator, the passive component and the rewiring structure, after which the carrier substrate is removed.
The method according to the invention has the advantage that an extremely compact electronic device that already has all the required contacts can thus be produced in a rapid and efficient manner. The electronic device is suitable in particular for mounting on a printed circuit board or the like.
A first embodiment of the method according to the invention provides the now described method steps. After the provision of the carrier substrate, a photofilm layer is applied on the first surface of the carrier substrate. After the exposure of the photofilm layer using a mask which images line structures, the photofilm layer is developed, the imaged line structures are removed from the photofilm layer. The developed regions are filled with an electrically conductive layer, after which the photofilm layer is removed. As a result, a three-dimensional rewiring structure is formed from the electrically conductive layers. The passive component is applied on the first surface of the carrier substrate. Afterward, the insulator is applied on the first surface of the carrier substrate, so that it is located above the passive component.
Afterward, electrical connections are produced between first and second through contacts in the insulator and electrical terminals of the passive component. The semiconductor chip is applied on the insulator, after which wire bonding connections are produced between first contact areas of the semiconductor chip and first contact pads of the rewiring structure. Electrical connections are subsequently produced between second contact areas of the semiconductor chip and the first and second through contacts of the insulator. A housing made of plastic is provided around the semiconductor chip, the insulator, the passive component and the rewiring structure. Finally, the carrier substrate is removed resulting in external contact areas of the electronic device being uncovered.
The method is associated with the advantage that it is possible to produce a compact and cost-effective electronic device that contains at least one semiconductor chip and at least one trimmable passive component.
Copper, in particular, is suitable as the carrier substrate, and can be removed by etching or by mechanical abrasion, such as, for example, grinding, after the application of the housing made of plastic.
In accordance with a further embodiment of the method according to the invention, aluminum, nickel, silver, gold, palladium and/or copper is used for the electrically conductive layer of the rewiring structure; these metals have the advantage of good electrical conductivity.
A further embodiment of the method according to the invention provides for the electrically conductive layer of the rewiring structure to be applied by sputtering and/or vapor deposition. The process of filling with the electrically conductive layer can also be effected, for example, by paste printing or by electrodeposition or chemically. Complex rewiring structures in electronic devices can advantageously be produced very rapidly and simply by the methods mentioned.
The housing of the electronic device may advantageously be produced from plastic by transfer molding. The method has the advantage of simple and cost-effective produceability. Moreover, in this case the wire bonding connections are preserved and protected against being torn away. Thus, the entire structure produced, including the semiconductor chip and the bonding wires, can be encapsulated by molding using a commercially available molding compound, globe top or the like.
To summarize, the following aspects of the invention emerge. A semiconductor component with a trimmable passive component in a planar xe2x80x9cleadlessxe2x80x9d housing is provided. The configuration contains a semiconductor chip that is positioned and contact-connected on a passive component (resistor, coil or capacitor) in a so-called xe2x80x9cleadlessxe2x80x9d housing. The passive component can be adjusted after mounting. The housing can be mounted onto a printed circuit board or onto a substrate in two variations given corresponding configuration of the contacts.
The passive component can be adjusted or trimmed by a laser, for example. This is desirable, particularly in radio-frequency applications, for impedance or capacitance matching, since tolerances of the electrical properties of the semiconductor chip can be compensated for in this way. By way of example, the following manufacturing sequence is suitable as a production method. A metallization layer is applied to a carrier (for example copper) by phototechnology and electrodeposition. The metallization layer may have, as required, a staircase structure if through-plating is desired. The carrier is equipped with a passive component, after which a semiconductor chip is mounted and contact-connected. The structure is potted or encapsulated by injection molding on one side. Afterward, the carrier is removed by selective etching, damage to the metallization structure being precluded. If appropriate, a protective coating, for example made of gold, can be applied to the uncovered contact pads. In addition, the passive component can be covered with an insulation layer, for example with a soldering resist.
In an alternative method, the passive component can likewise be constructed in a manner employing phototechnology by its structure being introduced into the photofilm layer in a manner employing mask technology and the structure subsequently being provided with a metallization layer. By way of example, a spiral structure of a coil can be produced in this way. A further alternative may consist in the carrier substrate not being completely removed, but rather being utilized to produce the passive component. Thus, by way of example, the spiral structure of a coil can be produced by selective etching.
A resistor as the passive component can be applied e.g. by lamination, by screen printing, spinning on or the like of corresponding material onto the carrier substrate; merely an insulator is then placed thereon.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an electronic device having a trimming possibility and at least one semiconductor chip and a method for producing the electronic device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.